Hi
No brute force was used or excessive torque applied in tightening The lock-keeper bolts.
Insert the taper into the socket half to two thirds of the length of the taper and quick flick of the wrist to slap it home.
Then always used the method taught in the mid 20 th century to nip up lock bolts on morse tapers.
Thumb on the head of the spanner that is on the nut and gentle squeeze using the pinky and ring finger to nip up just firm.
Eric